Ferrous sulphate is also known as iron sulphate, common uses for this ingredient are for people with iron deficiency. Iron levels have been found to decline due to exercise (79) with findings showing that it can help with fatigue (80).
79 – Weaver, C. M., & Rajaram, S. (1992). Exercise and iron status. The Journal of nutrition, 122(3 Suppl), 782-787.
80 – Brutsaert, T. D., Hernandez-Cordero, S., Rivera, J., Viola, T., Hughes, G., & Haas, J. D. (2003). Iron supplementation improves progressive fatigue resistance during dynamic knee extensor exercise in iron-depleted, nonanemic women. The American journal of clinical nutrition, 77(2), 441-448.